There is not a lot of 1st gen information that breaks down the powertrains down to the axles and combinations so I am having a difficult time finding the truth. I can't tell what is TYPO's (GM Brochures, and documentation is just FULL of bad typo's) and what are upgrades. Before anything goes on my site, I research and cross-reference between 1000's of sheets of information along with books, online resources, brochures, and magazines.. But there is not a lot of information with this deep of combinations on the 1st gen's..

My NOR 01C 69 RS probably had a 307 in it originally (original engine had been removed by the time I purchased the car in 1991 and replaced with a 327). It still has the original PG transmission and open rear end with 2.73 gears. Gearing verified by axle code and stamping a on the OD of the pinion gear. Can supply pictures later if needed. Currently at 33,000 ft traveling on business and don't have pics with me.